Grinding method



July 12, 1966 s, M* NAPP 3,260,019

GRINDING METHOD Filed April 18, 1963 INVENTOR.

United States Patent O 3,260,019 GRINDING METHOD Sidney M. Napp, Rockton, Ill., assignor to Besly-Welles Corporation, South Beloit, Ill., a corporation of Illinois 'Filed Apr. 18, 1963, Ser. No. 274,000 4 Claims. (Cl. 51-281) This invention relates generally to grinding, and specifically to a method of grinding.

Accordingly a primary object of the invention is to provide a mehod of grinding workpieces, particularly oddshaped pieces, to very close tolerances.

Another object is to provide a mehod of grinding in which the workpiece -is controllably rotated as it travels in a grinding zone.

Yet another object is to provide a method of grinding workpieces which must be rotated as they are ground for best results in a double-disc grinder.

Other objects and advantages of the invention will become apparent from the following description of the invention.

The invention is illustrated more or less diagrammatically in the accompanying drawing wherein:

FIGURE l is a side elevation, with parts broken away for clarity, of the workholder assembly; and

FIGURE 2 is a view taken substantially along the line 2-2 of FIGURE 1.

Like reference numerals will refer to like parts throughout the following description of the drawing.

Referring first to FIGURE l, a pair of guide rails are indicated generally at and 11. A workholder assembly, indicated generally at 12, is supported at the advancing end of a pusher bar 13, the workholder assembly riding along the guide rails 10 and 11 on a pair of rollers 14 and 15.

The workholder assembly 12 includes a pair of substantially identical side plates 16, 17, which are secured by screws 18, 19, to pusher bar 13. The side plates are spaced from one another by a spacer whose boundaries are partially co-extensive with the boundaries of the side plates. The spacer is also connected to the pusher bar 13 by the screws 18 and 19. The upper and lower edges of the side plates extend above and below, respectively, the upper and lower edges of the spacer to form a pair of anges 21, 22, which are spaced apart a distance sulcient to straddle the guide rails 10 and 11. The rollers 14 and 15 are suspended between the flanges 21 and 22 by bolts 23, 24, as best seen in FIGURE 2. The rollers are located in the center of cut-away areas 25, 26 in the spacer. Spacer 20 is bored as at 27, 28, to form a passageway for a roller chain 29.

A pair of annular retainer plates are indicated at 30 and 31. The retainer plates are secured to spacer 20 by a plurality of bolts 32.

A workholder is indicated generally at 33. In this instance the workholder is formed with a circular internal bore except for a chordial section 34 for reception of an odd-shaped workpiece 35 whose outline is indicated by dotted lines in FIGURE l. The workholder includes a tongue portion 36 which extends radially outwardly about the circular periphery of the workholder. The tongue is received between the overhanging an ges formed by retainer plates 30 and 31. An insert sprocket 37 is secured to the tongue 36 by a plurality of pins or Wedges 38.

The tongue portion 36 of the workholder is apertured at a plurality of locations, one of which is indicated at 40 in FIGURE 2. The apertures are radially equidistant from center 44 and they may be equidistantly spaced circumferentially from one another. The opposed, inner faces of retainer plates 30, 31 have bearing races 41, 42, formed therein, the bearing races being aligned with the apertures 40. A pair of ball bearings is received in each bore 40, the ball bearings resting in races 41 and 42-of the retainer plates 30, 31.

Preferably retainer plates and workholder are hardened. The width of the assembly will, of course, be narrower than the clearance between the grinding discs if the apparatus is used with a double disc grinding machine. If only one side of a workpiece is to be ground the side of the workholder assembly facing the grinding disc must be displaced inwardly a distance suicient t0 clear the disc as the workholder traverses the grinding zone.

The use and operation of the invention are as follows:

Assume that a workpiece of a generally triangular configuration, such as workpiece 35 in FIGURE 1, is to be ground between the discs of a double disc grinding machine, one of which is illustrated at 45 in FIGURE 1. The workpiece is inserted into the workholder 33 by any suitable feeding device. The entire assembly is advanced toward the grinding zone by a force exerted on the pusher bar 13.

Roller chain 29 is rotated as the workholder assembly advances toward the grinding zone. Any suitable structure'may be employed to rotate the chain, including a fixed driving sprocket located intermediate the end travel points of the roller chain or a driving sprocket which moves with the pusher bar. The particular relationship between the roller chain driving means and the workholder assembly and its driving portion may be varied. It is, however, essential that the roller chain rotate with respect to the pusher bar.

Movement of the roller chain in a direction indicated by the dotted arrows causes workholder 33 to rotate in the direction of the curved arrow since the roller chain is in engagement with the insert sprocket 37. Workholder 33 rotates freely with respect to retainer plates 30, 31 due to the action of ball bearings 41, 42 which ride in the bearing races formed in the internal, opposite faces of retainer plates 30, 31.

The workholder, and the workpiece carried by it, rotate about a xed center of rotation 44 which may fall within or without the boundaries of the workpiece.

In the illustrated embodiment the center of rotation falls in an internal aperture in the workpiece 35. Center of rotation 44 traverses a linear path since guide rails 10 and 11 are parallel to one another. In this instance the center of rotation 44 is shown as lying on the horizontal center line of the grinding discs and accordingly the center of rotation will follow a rectilinear path which is coextensive with the horizontal center line of the grinding discs as the workpiece passes through the grinding zone. It should be clearly understood, however, that this particular arrangement may be varied within the scope of the invention.

Although a preferred embodiment has been illustrated and described and several alternative embodiments have been discussed, it will at once be apparent to' those skilled in the art that further modifications and variations may be employed within the scope of the invention. Accordingly it is intended that the scope of the invention be limited, not by the foregoing exemplary description, but solely by the scope of the hereafter appended claims when interpreted in light of the pertinent prior art.

I claim:

1. In the method of grinding a planar surface on a workpiece, the steps comprising orienting a workpiece having a planar surface to be ground with the planar surface disposed in a plane generally coincident with the grinding plane of a rotating, axially fixed grinding wheel in a grinding zone,

moving the center of the workpiece laterally past the 3 4 grinding wheel along a continuously advancing rec- 4. The method of claim 3 further characterized in that tilinear path of travel which is oriented at right the rectilinear path of the workpiece is co-extensive with angles to the axis of rotation of the grinding wheel, a center line of grinding zone. maintaining the planar surface to be ground in the grinding plane as the workpiece is advanced into, 5 RefelellCeS Cied by the Examiner through, and Out Of the grinding 20116 t0 a point lll its path of travel at which the workpiece leaves contact with the grinding Wheel, and 540324 6/1895 Luther 51-123 positively imparting rotational movement having a COD- g174 3/1909 Hanson 51-123 Stant peripheral velocity to the workpiece during the l0 l 928 5/1918 Helm 51- 215 time i1; is in Contact with the grinding wheel. 1735333 11/1929 Olson 51-236 2, The method of claim 1 further including the step of 1973 5 11 9/1934 Schmalz 51- 281 moving the workpiece past a pair of rotating, axially 2110931 3/1938 Dyer et al' 51"236 X fixed grinding wheels in a grinding zone, 2328809 9/1943 Johnson 51-236 X said grinding wheels having grinding surfaces which 15 8/ 192g 511x h 51-236 lie in two parallel grinding planes whereby a pair 2990659 61 Besk Ta "515E-8 of parallel surfaces on the workpiece may be simultaneously ground.

3. The method of claim 1 further characterized in that LESTER M SWINGLE Pnma'y Examme the rectilinear path of the center of rotation of the work- 20 JOHN C. CHRISTIE, Examiner. piece is substantially parallel to a center line of the grind- 1 E PEELE Assistant Examiner mg zone. 

1. IN THE METHOD OF GRINDING A PLANAR SURFACE ON A WORKPIECE, THE STEPS COMPRISING ORIENTING A WORKPIECE HAVING A PLANAR SURFACE TO BE GROUND WITH THE PLANAR SURFACE DISPOSED IN A PLANE GENERALLY COINCIDENT WITH THE GRINDING PLANE OF A ROTATING, AXIALLY FIXED GRINDING WHEEL IN A GRINDING ZONE, MOVING THE CENTER OF THE WORKPIECE LATERALLY PAST THE GRINDING WHEEL ALONG A CONTINUOUSLY ADVANCING RECTILINEAR PATH OF TRAVEL WHICH IS ORIENTED AT RIGHT ANGLES TO THE AXIS OF ROTATION OF THE GRINDING WHEEL, MAINTAINING THE PLANAR SURFACE TO BE GROUND IN THE GRINDING PLANE AS THE WORKPIECE IS ADVANCED INTO, THROUGH, AND OUT OF THE GRINDING ZONE TO A POINT IN ITS PATH TO TRAVEL AT WHICH THE WORKPIECE LEAVES CONTACT WITH THE GRINDING WHEEL, AND POSITIVELY IMPARTING ROTATIONAL MOVEMENT HAVING A CONSTANT PERIPHERAL VELOCITY TO THE WORKPIECE DURING THE TIME IT IS IN CONTACT WITH THE GRINDING WHEEL. 